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| /*
| * arch/sh/kernel/cpu/sh5/switchto.S
| *
| * sh64 context switch
| *
| * Copyright (C) 2004 Richard Curnow
| *
| * This file is subject to the terms and conditions of the GNU General Public
| * License. See the file "COPYING" in the main directory of this archive
| * for more details.
| */
|
| .section .text..SHmedia32,"ax"
| .little
|
| .balign 32
|
| .type sh64_switch_to,@function
| .global sh64_switch_to
| .global __sh64_switch_to_end
| sh64_switch_to:
|
| /* Incoming args
| r2 - prev
| r3 - &prev->thread
| r4 - next
| r5 - &next->thread
|
| Outgoing results
| r2 - last (=prev) : this just stays in r2 throughout
|
| Want to create a full (struct pt_regs) on the stack to allow backtracing
| functions to work. However, we only need to populate the callee-save
| register slots in this structure; since we're a function our ancestors must
| have themselves preserved all caller saved state in the stack. This saves
| some wasted effort since we won't need to look at the values.
|
| In particular, all caller-save registers are immediately available for
| scratch use.
|
| */
|
| #define FRAME_SIZE (76*8 + 8)
|
| movi FRAME_SIZE, r0
| sub.l r15, r0, r15
| ! Do normal-style register save to support backtrace
|
| st.l r15, 0, r18 ! save link reg
| st.l r15, 4, r14 ! save fp
| add.l r15, r63, r14 ! setup frame pointer
|
| ! hopefully this looks normal to the backtrace now.
|
| addi.l r15, 8, r1 ! base of pt_regs
| addi.l r1, 24, r0 ! base of pt_regs.regs
| addi.l r0, (63*8), r8 ! base of pt_regs.trregs
|
| /* Note : to be fixed?
| struct pt_regs is really designed for holding the state on entry
| to an exception, i.e. pc,sr,regs etc. However, for the context
| switch state, some of this is not required. But the unwinder takes
| struct pt_regs * as an arg so we have to build this structure
| to allow unwinding switched tasks in show_state() */
|
| st.q r0, ( 9*8), r9
| st.q r0, (10*8), r10
| st.q r0, (11*8), r11
| st.q r0, (12*8), r12
| st.q r0, (13*8), r13
| st.q r0, (14*8), r14 ! for unwind, want to look as though we took a trap at
| ! the point where the process is left in suspended animation, i.e. current
| ! fp here, not the saved one.
| st.q r0, (16*8), r16
|
| st.q r0, (24*8), r24
| st.q r0, (25*8), r25
| st.q r0, (26*8), r26
| st.q r0, (27*8), r27
| st.q r0, (28*8), r28
| st.q r0, (29*8), r29
| st.q r0, (30*8), r30
| st.q r0, (31*8), r31
| st.q r0, (32*8), r32
| st.q r0, (33*8), r33
| st.q r0, (34*8), r34
| st.q r0, (35*8), r35
|
| st.q r0, (44*8), r44
| st.q r0, (45*8), r45
| st.q r0, (46*8), r46
| st.q r0, (47*8), r47
| st.q r0, (48*8), r48
| st.q r0, (49*8), r49
| st.q r0, (50*8), r50
| st.q r0, (51*8), r51
| st.q r0, (52*8), r52
| st.q r0, (53*8), r53
| st.q r0, (54*8), r54
| st.q r0, (55*8), r55
| st.q r0, (56*8), r56
| st.q r0, (57*8), r57
| st.q r0, (58*8), r58
| st.q r0, (59*8), r59
|
| ! do this early as pta->gettr has no pipeline forwarding (=> 5 cycle latency)
| ! Use a local label to avoid creating a symbol that will confuse the !
| ! backtrace
| pta .Lsave_pc, tr0
|
| gettr tr5, r45
| gettr tr6, r46
| gettr tr7, r47
| st.q r8, (5*8), r45
| st.q r8, (6*8), r46
| st.q r8, (7*8), r47
|
| ! Now switch context
| gettr tr0, r9
| st.l r3, 0, r15 ! prev->thread.sp
| st.l r3, 8, r1 ! prev->thread.kregs
| st.l r3, 4, r9 ! prev->thread.pc
| st.q r1, 0, r9 ! save prev->thread.pc into pt_regs->pc
|
| ! Load PC for next task (init value or save_pc later)
| ld.l r5, 4, r18 ! next->thread.pc
| ! Switch stacks
| ld.l r5, 0, r15 ! next->thread.sp
| ptabs r18, tr0
|
| ! Update current
| ld.l r4, 4, r9 ! next->thread_info (2nd element of next task_struct)
| putcon r9, kcr0 ! current = next->thread_info
|
| ! go to save_pc for a reschedule, or the initial thread.pc for a new process
| blink tr0, r63
|
| ! Restore (when we come back to a previously saved task)
| .Lsave_pc:
| addi.l r15, 32, r0 ! r0 = next's regs
| addi.l r0, (63*8), r8 ! r8 = next's tr_regs
|
| ld.q r8, (5*8), r45
| ld.q r8, (6*8), r46
| ld.q r8, (7*8), r47
| ptabs r45, tr5
| ptabs r46, tr6
| ptabs r47, tr7
|
| ld.q r0, ( 9*8), r9
| ld.q r0, (10*8), r10
| ld.q r0, (11*8), r11
| ld.q r0, (12*8), r12
| ld.q r0, (13*8), r13
| ld.q r0, (14*8), r14
| ld.q r0, (16*8), r16
|
| ld.q r0, (24*8), r24
| ld.q r0, (25*8), r25
| ld.q r0, (26*8), r26
| ld.q r0, (27*8), r27
| ld.q r0, (28*8), r28
| ld.q r0, (29*8), r29
| ld.q r0, (30*8), r30
| ld.q r0, (31*8), r31
| ld.q r0, (32*8), r32
| ld.q r0, (33*8), r33
| ld.q r0, (34*8), r34
| ld.q r0, (35*8), r35
|
| ld.q r0, (44*8), r44
| ld.q r0, (45*8), r45
| ld.q r0, (46*8), r46
| ld.q r0, (47*8), r47
| ld.q r0, (48*8), r48
| ld.q r0, (49*8), r49
| ld.q r0, (50*8), r50
| ld.q r0, (51*8), r51
| ld.q r0, (52*8), r52
| ld.q r0, (53*8), r53
| ld.q r0, (54*8), r54
| ld.q r0, (55*8), r55
| ld.q r0, (56*8), r56
| ld.q r0, (57*8), r57
| ld.q r0, (58*8), r58
| ld.q r0, (59*8), r59
|
| ! epilogue
| ld.l r15, 0, r18
| ld.l r15, 4, r14
| ptabs r18, tr0
| movi FRAME_SIZE, r0
| add r15, r0, r15
| blink tr0, r63
| __sh64_switch_to_end:
| .LFE1:
| .size sh64_switch_to,.LFE1-sh64_switch_to
|
|
